Computationally efficient optimal power allocation algorithms for multicarrier communication systems

Abstract

Abstract-In this paper, we present an optimal, computationally efficient, integer-bit power allocation algorithm for discrete multitone modulation. Using efficient lookup table searches and a Lagrange-multiplier bisection search, our algorithm converges faster to the optimal solution than existing techniques and can replace the use of suboptimal methods because of its low computational complexity. Fast algorithms are developed for the data rate and performance margin maximization problems.

Adaptive BICM-OFDM Systems

“…(3) has been solved by the authors via expansion to coded systems of the well known bisection approach used by Krongold et al [1]. The set of all rate-power pairs at a given BER/FER P Target of all allowed transmission modes, employing SNR thresholds obtained from AWGN simulation as well as analytical expressions for uncoded M -QAMs, has been used to find a convex set allowing for a convex optimisation solution of (3) via Lagrangian multipliers [10].…”

“…In order to carry out the optimisation, the rates have to be formulated as explicit functions of the powers, such that r k = f (p k ), which in case of coded systems with finite symbol alphabets is a non-trivial problem. If channel coding is neglected, analytical BER/FER expressions, e.g., for M -QAM modulations, can be used [1][2][3]. Due to the difficulties in finding analytical expressions for the FER of coded systems, however, the simulated performance of different code and modulation combinations is often utilised to quantify the performance [8,10].…”

“…Early works focused on uncoded BER optimisation [1][2][3], but nowadays the consideration of channel coding into bit and power loading schemes has become a major aspect. Several contributions to this field have been made, especially considering the influence of Bit Interleaved Coded Modulation (BICM) on such systems.…”

Cognitive Radio Dynamic Access Techniques

“…In [18] the optimal and suboptimal power allocations are combined with Coded Weak Sub Carrier Excision (CWSE) method, where the weak subcarriers are excluded from transmission. Power allocation with objective to maximize the bit rate subject to a finite total allocated power and minimizing the total power allocation subject to a finite target rate optimization problem are decribed in [19], while in [20] a look up table, to find rate-SNR operating point, and Lagrange multiplier bisection search method are applied to calculate the allocated power on each carrier.…”

Diversity vs. adaptivity in multiple antenna systems

“…The most prominent example is the Hughes-Hartogs algorithm [1], but there also exist far more efficient implementations that exploit the convexity of the rate-power region, e.g. [8]. Note that instead of simple scaling it is, of course, also possible to redistribute the transmit powers according to [7] once the bit allocation has been found.…”